In recent years, SD™ memory cards have been widely used as data memory devices for photographs. It is hoped that SD memory cards can be used in applications where the maintainability of once-created files is important, such as photographs for official materials.
In such applications, SD memory cards need to be provided with the following characteristics:                Photographic data once recorded on an SD card cannot be erased, changed, or falsified later.        Photographic data taken by a conventional digital camera can be recorded.        Photographic data can be read by an ordinary PC and USB reader/writer.        
Various methods of handling data with an SD card have been proposed. One of them has been disclosed in, for example, Jpn. Pat. Appin. KOKAI Publication No. 2006-040264. However, there has been no SD memory card with all the above characteristics. Accordingly, it is difficult to use SD memory cards in applications where the maintainability of files is important.